Matter Element and MaterialP

[danielkallendorf]

Matter

Provide a proposed name for the lattice element. This can be an abbreviation, and should be at most 1-2 words (e.g., Quadrupole).

Matter Element (replaces foil)

Materials which fully occupy the beamline, like targets, (stripper-)foils, vacuum windows, gas cells or degraders.
This element can cause energy-loss, angualar and energy straggling, as well as change of charge state or particle type.

MaterialP: Definition of materials

The definition of materials is inspired by Geant4's material handling. One can either use the name, which is the symbol of an element ("G4_Cu", "G4_H", ...) or compound ("G4_STAINLESS-STEEL").
In the future all elements and materials in the G4 Manual will be supported.

Alternatively custom elements can be defined by

ElementP:
- name:      # [string] The name of the material
- density:   # [g/cm^3] The density of the material
- Z:         # [int]    The atomic number
- A:         # [int]    The mass number (equals Z+N)
- N:         # [int]    The neutron number
- m:         # [g/mol]  The atomic mass

and compound by

CompoundP:
- name:      # [string] The name of the material
- density:   # [g/cm^3] The density of the material
- elements:  # List of MaterialP
- ratio:     # List of ratios of the elements

Physical model

I assume a material should be described precise enough by state, density, thickness and composition.

Note: Due to the stochastic nature of beam-matter interaction, the Taylor-/transfer-map-formalism can only account for the mean average effect.

[DavidSagan]

There are several issues that are raised here. For one there is the matter of units. Do we want to have a consistent set of units which would make densities kg/m^3? I know this looks kind of ugly but from a practical point of view it will lead to less errors.

[DavidSagan]

Another issue is material naming. For elements and compounds I would use the OpenPMD naming convention #33. And I would get away from the G4_ prefix unless, for a particular material, there is a good reason not to.

[DavidSagan]

Another issue is that having a single Matter element to represent foils, gas cells, etc. to my mind lumps too many different types of objects under one name. I would rather see separate elements. Especially since the parameter set needed for these different types will undoubtedly be different.

[danielkallendorf]

Yes. density in kg/m^3 is ugly but reasonable. Do you have a suggestion for the atomic mass?

Is there a list of OpenPMD materials? I could not find any reference on that.

As someone working on fragment separators, to me everything is just matter with composition and shape.
What element specific parameters come to your mind?

[DavidSagan]

• You don't need atomic mass directly. EG: #3He is good enough.
• OpenPMD does not define materials yet. I propose adding to OpenPMD a materials list and then PALS can inherit from that. Much better to have everything is in one place.
• in terms of element parameters, there could be something like gas pressure that is needed. We should make a survey to see what people need.

Also: Vacuum windows was mentioned. This should definitely be in a category by itself.

[EZoni]

@danielkallendorf

There are a few conflicts to be resolved after the latest merge in main. Could you resolve the conflicts and apply the suggestions from @DavidSagan's review? Thanks!

[ax3l]

Small typo:

Suggested change

	and compunds by
	```{code} yaml
	CompundP:
	and compounds by
	```{code} yaml
	CompoundP:

[danielkallendorf]

Comments from today: define ratios more precise (mass/number of atoms/...)
Allow for Compounds of Compounds or introduce an intermediate element